The present invention relates to a multi-layer aerating filter, in particular, to an apparatus for aquaculture and providing a better filtering function.
The most important task in aquaculture is to maintain proper quality of the water in aquaria for the need of water plants and animals for human use or consumption. The economical and effective method is to circulate aquarium water through a filtering apparatus to eliminate the detrimental materials and to ensure the purity of the water when reusing it.
Conventionally, the filtering apparatus employ filter materials contained therein to hold back contaminants. Nevertheless, the filtering functions of the known apparatus are unsatisfactory because they have many drawbacks. For example, the effective infiltration area of the filter material used in the conventional filtering apparatus is restricted by its exterior surfaces, and this area is usually small. It is easy to accumulate a large amount of contaminants on the surfaces of the filter material and to clog the infiltration passage in a short period, and, therefore, the flow rate of circulating water decreases. As a result, the oxygen provision for the nitrifying bacteria in the filter material becomes insufficient. It is difficult to culture nitrifying bacteria and the organisms can not be adequately digested by enough nitrifying bacteria.
Furthermore, in the case of aeration operation, a great amount of oxygen is dissolved into water, and the harmful impurities is strained out such that the filtering function is more effective. However, there is no such design utilizing aeration process in the conventional filtering apparatus.